(1) Field of the Invention
The present invention is directed to a method for designing an acoustic array and more particularly to a method for designing an acoustic array with simplified wiring and processing.
(2) Description of the Prior Art
Beamforming is used in active and passive sonar to increase the efficiency or gain from an array of transducers. In such an array, each transducer is separately wired to acoustic processing equipment. The acoustic processing equipment adjusts the power and time delay associated with the joined transducer. This requires separately controlling the signal associated with each array element.
Conventional arrays modify beam patterns to lower sidelobes by electrically shading the outputs of a number of elements, or less effectively, by using multiple elements in a series parallel connection. It is known that types of hydrophones, such as PVDF hydrophones, can be shaped so as to achieve the same, reduced sidelobe levels as a number of electrically shaded elements thereby eliminating the electronics and saving space. It has been shown that a single element can be shaped as a linear tapered element or an element shaped to an approximation of a −40 dB Chebyshev shading function can be used to reduce the sidelobes from that which would be expected with a rectangular element. These single elements are mounted to a cylindrical surface before use. These methods teach suppression of sidelobes by area shading, but they don't teach a method for designing an acoustic transducer or sensor to a preferred beam pattern.
Curved and doubly curved geometries are known for active and passive sonar arrays; however, in the prior art, the array shape is dictated by the underlying object, not the beam pattern. Electronic shading is typically used for giving a preferred beam pattern. One such array is given by U.S. Pat. No. 6,711,096 to Kim C. Benjamin. Also known are methods for making arrays having conforming shapes such as that given in U.S. Pat. No. 6,255,761 to Benjamin.